There is a need for apparatuses which safely and effectively bioprocess a circulating a body fluid, such as whole blood or plasma. As an example, the development of liver support apparatuses has progressed from passive or removal systems to bioactive or biochemical systems. The passive systems have included hemodialysis, hemoperfusion, plasma exchanges, etc. for removing the blood toxins which accumulate during liver failure.
The successful reports of orthotopic liver transplantation in prolonging life has led to the conceptual development of biochemical or cell based liver support systems. These systems consist mainly of bioreactors containing cells. For example, a bioartificial liver device may include a hollow fiber cartridge containing primary pig liver cells. The liver cells are seeded in the extracapillary space of the hollow fibers, and blood or plasma is perfused through the lumen of the fibers. Microporous hollow fibers permit passage of plasma proteins but prevent the passage of cells (e.g., blood cells and liver cells), thereby allowing the transport of soluble and protein-bound substances from the plasma across the hollow fiber walls and into the space occupied by the porcine hepatocytes.